Enuresis bed pad

ABSTRACT

An enuresis bed pad is constructed with a plurality of parellel electrically conductive sensor strips which are bonded to but not embedded in, nor flush with, one surface of an essentially nonstretchable, water-proof, electrically insulative substrate. The sensor strips are spaced on the substrate so that they are normally electrically insulated. The complete structure is relatively thin, flexible and crease resistant. When any two adjacent sensor strips are bridged electrically by the electrolytes in urine, an external circuit is closed and audible and/or visual signals are activated. The sleeping person is awakened.

United States Patent v [191 Shuman Dec. 11, 1973 Kroening et al. ZOO/61.05

2/1954 Kaplan 200161.05 8/1930 Van Guilder ZOO/61.05

Primary Examiner-J. R. Scott Att0rney-Richard S. Shreve, Jr.

[57] ABSTRACT An'enuresis bed pad is constructed with a plurality of parellel electrically conductive sensor strips which are bonded to but not embedded in, nor flush with, one surface of an essentially non-stretchable, water-proof, electrically insulative substrate. The sensor strips are spaced on the substrate so that they are normally electrically insulated. The complete structure is relatively thin, flexible and crease resistant.

When any two adjacent sensor strips are bridged electrically by the electrolytes in urine, an external circuit is closed and audible and/or visual signals are activated. The sleeping person is awakened.

3 Claims, 9 Drawing Figures //d l l L //b ENURESIS BED PAD BACKGROUND OF THE INVENTION Multiple sheet sensor pads for enuresis have been in use many years. These consist of a top perforated metal foil sheet or screen, a larger size insulating sheet and a bottom foil sheet. These devices must be assembled and aligned each night. They are subject to false signals (no urine flow) due to shifting or by metal sliver penetration. Such false signals slow or even defeat the training or conditioning process. In addition the sheets are not durable because of contact each night with urine. They are not readily sanitized and are crinkly and messy to handle after each use.

When the two metal components are bridged electrically by the electrolytes in urine, an external circuit is energized. The latter is usually designed with a sensitive relay. With the flow of urine an alarm is sounded which wakes the user. The circuits are such that the current at the pad is so miniscule that it would not be felt even if the pad were in contact with the bare buttocks of a child or infant.

In Seiger U.S. Pat. No. 2,127,538, the aforementioned objections to the multiple sheet pads are overcome by first fabricating comb-like contact elements and embedding these in a soft rubber substrate, so that they are flush with one surface of a soft rubber substrate, but with one surface of the contact elements exposed. The complete structure results in a unified single sheet sensor pad. The single sheet pad is easy to use, is false-signal-proof, and generally effects faster trainmg.

The design of such a pad does not make it adaptable to continuous manufacture and the prefabricated comb-like contacts are difficult to handle, as the average pad is approximately 18 X 26 inches. Fabrication of these delicate comb like contacts involves substantial labor costs. Embedding by pressure and/or heat or even by a casting and curing process, makes the per unit cost high. The marketing of such devices is generally done on a rental basis only, and at a very high cost.

In Seiger U.S. Pat. No. 2,644,050 greater ease of manufacturing is discussed, through use of a plurality of comb-like contact elements which are shorter and easier to handle. These are embedded, but flush with one surface of the substrate. A collateral benefit is discussed which states that such a pad has greater flexibility and durability. In either types we are faced with an individual lay up operation for each pad.

The object of my invention is to provide a single sheet urine flow control pad with the aforementioned advantages and with a structure that is readily adaptableto a continuous fabrication process, that is to say, on a roll to roll basis. All that remains to complete the pad, after automatically cutting to sheet size, is to provide polarity collector strips and terminals which is readily accomplished with little additional labor.

A further object is to provide a single sheet enuresis pad which is low in cost. The pad manufactured according to my structure and method achieves the same result and is used in the same manner as other high cost pads. Thus, many people suffering from enuresis are not economically barred from taking advantage of what is recognized as the best type of pad (single sheet) to end the enuresis problem.

Another object is to provide a low cost single sheet enuresis pad which may be purchased outright and not rented. This relieves the trainee and family of the psychological pressures to achieve satisfactory results within a specific time limit. The pad of the present invention and the ancillary signal unit are also available for a second child with little or no extra costs.

SUMMARY OF THE INVENTION The present invention relates to the fabrication of a structure resulting in a single sheet urine flow sensor pad. Thin current conducting sensor strips are bonded to one surface of a sheet-like, essentially nonstretchable, relatively flexible and crease resistant and electrically insulative substrate, but not embedded not flush with the surface thereof. The sensor strips are parallel and insulated from each other by the supporting sheet.

The pad described in this invention is most economically fabricated on a roll to roll sequence. After the sheet is fabricated with the bonded sensor strips in place, it may be cut to any desired length and two polarity collector elements are electrically connected to alternate and non-adjacent sensor strips. One of the two polarity collector strips is attached to the first, third, fifth, etc. sensor strip at one end of the pad. The other sensor strips, that is, the second, fourth, sixth, etc. are attached to a second polarity collector strip which is electrically insulated from said first collector strip. Attachment is accomplished in a manner so as to provide electrical continuity.

Terminals or connecting wires are attached at one edge of the pad for convenience in actual use. The one is directly connected to the polarity collector strip at that end of the pad and the second is connected to a sensor strip which in turn is attached to the polarity collector strip at the other end. In effect, the latter sensor strip functions as a part of a polarity collector strip. It may be made somewhat thicker than the other sensor strips. Thus, any two sensor strips are of opposite polarity and may be electrically bridged by the electrolytes in urine.

The structure and fabricating technique overcome the problems of handling, positioning, and embedding delicate comb-like electrodes in a soft rubber substrate. This could entail almost complete hand assembly.

BRIEF DESCRIPTION OF THE DRAWING Referring to the drawings:

FIG. 1 is top plan view of urine flow sensor pad.

FIG. 2 is bottom view of FIG. 1.

FIG. 3 is an enlarged section of FIG. 1 taken on Lines 3-3.

FIG. 4 is a fragmentary view illustrating a punched polarity tab and polarity collector strip ready for application.

FIG. 5 is a section on line 5-5 of FIG. 1.

FIGS. 6 & 7 are viewstaken on line 6-6 and 77, respectively.

FIG. 8 is a fragmentary bottom view of FIG. 5.

FIG. 9 is a diagramatic illustration of the external electrical signal circuit.

DETAILED DESCRIPTION OF DRAWINGS AND PREFERRED EMBODIMENTS Referring to the drawings the complete single sheet enuresis pad is shown in FIG. 1. The substrate 10 has bonded to its one surface the several spaced electrically conductive sensor strips 11. The polarity collector strips 13 and 13a are attached to alternate sensor strips on the other side of the substrate via the punched polarity tabs 14. Leads 16 and 16a and insulated terminal connector wires 17 are attached to selected sensor strips 11a and 11b, FIG. 1 as shown. It is understood that the wires 17 are stripped at their ends for electrical attachment to leads. The leads and polarity collector strips are protected and insulated by covering with waterproof insulating tape 20. It will be noted that lead 16a is connected and insulated from polarity collector strip 13. The sensor strip to which it is connected 11a serves as part of the polarity collector strip 130. There is an advantage to the indicated positioning'of the leads arranging for two sensor strips between both. Even if electrical bridging by urine occurs between sensor strips 11a and 11b near leads, the current path and electrical conductivity is about the same as at any other point on the pad. The tape shown on the long sides of FIGS. 1 and 2 are not functional but decorative.

When the circuit is closed by electrolyte bridging, connector wires 17 which are attached to wires 27 or FIG. 9 energize relay coil 23 which pulls in armature 25 to relay contact 22 when main switch 24 is closed. Battery 21 then causes buzzer 26 to emit its signal which wakes the trainee. A 3-6V battery is generally used.

FIG. 3 shows in section the substrate 10 with the spaced sensor strips 11 and waterproof bonding material 12. While these are bonded to one surface of substrate but not embedded nor flush with said substrates surface, the combined total height of 11 and 12 or 18, is approximately 3 to 5 mils. This protrusion from the surface is small and does not pose a discomfort problem to the user. Since the pads are generally used under the top bed sheet, the protrusion is just not felt and the user is quite comfortable.

There are many ways in which the polarity collector strips may be attached to the sensor strips such as by, use of conductive cements, ultrasonic welding, or use of thin plastic clips. Attachment on the sensor strip side may also be achieved by tape insulation of alternate ends of sensor strips or by sensor strip end removal, cutting away alternate ends of alternate strips. The polarity collector strips can then be mounted on the sensor strip side.

In the preferred embodiment of my invention, one of the two polarity collector strips 13 is attached by disposing the punched polarity tabs 14 of FIG. 4 to the unlaminated side of the substrate 10. In FIGS. 4 and 5,'the polarity tabs are bent in a manner so as to dispose their conducting surfaces outward. A flexible conductive metal such as plain aluminum foil is folded over all the polarity tabs at each end of pad. In this manner there is no way in which the polarity collector strips can contact those sensor strips at the same end of pad, but without polarity tabs. This is accomplished efficiently with a special jig. After attachment, the polarity collector strips 13 are taped. In FIG. 8, the bottom view of the polarity collector strip is attached to a polarity tab, 14. It is understood that the polarity collector strip bridges across all the sensor strips on one side but separated by the substrate. The polarity collector strips are connected to alternate sensor strips via the punched polarity tabs.

Another important advantage with this method is that after taping, as previously described, the contact between the tabs and polarity collector strips is of a spring loaded character which is considered good electrical practice. This results from the resiliency of the bent substrate material. In addition, with the close confinement of the connection by tape, contact is always maintained, even if either tab or collector strip moves up or down.

In the preferred embodiment of my invention an excellent balance of non-stretchability and flexibility is achieved when I use a polyester film as a substrate. Particularly preferred are polyesters of terephthalic acid such as CELANAR (Celanese Plastics), MYLAR (Du- Pont) and MELINEX (ICI). It is not to be construed that this invention is limited only to this type of substrate.

A polyester film in the thickness range of 5-14 mils (with an optimal thickness of approximately 10 mils), has a very high tensile strength and tensile modulous. Such a film is subject to minimal dimentional change when used as an enuresis bed pad. Yet, the film is fairly flexible, comfortable in use and crease-resistant. These properties are important in maintaining the integrity of a the sensor strips. Additional treatment of the latter important factor will be covered under sensor strip specifications.

Biaxially oriented polypropylene treated to promote adhesion, polyimide and special types of 'polyamide (Nylon) films are also useful for substrate selection. In all instances films with no plasticizer or, if present, with non-migrating type, are recommended so that no reaction will occur when in contact with bonding adhesive.

Another important advantage in the use of tough- ,resilient, flexible and crease-resistant films as substrates, is that they tend to remain flat, that is, when flexed, they spring back to their original flat configuration as the enuretic trainee shifts and turns during sleep. In use the actual degree of convex or concave distortion is minimal, owing to the properties of the preferred types of films. Here again, this favors maintenance of sensor strip integrity. Kinking and fracture of these sensor strips are minimized.

In the preferred embodiment of my invention the sensor strips 11 of FIG. 1 are 2 to 3 mils-thick aluminum foil of low temper and with l to 2 mils of pressure sensitive adhesive or flexible heat sealable adhesive coated on one side of the foil. There are many, many adhesives of the latter types which bond well to aluminum and the substrate that can be supplied by several adhesive and/or adhesive tape manufacturers. Therefore, precise specification of this element is not needed here to teach the substance of the total invention. The sensor strips are approximately one-half inch wide, although this dimension is not critical. They are spaced about onefourth to five-eighths inch apart.

Although aluminum'foils are specifically mentioned, it is understood that the invention is not limited to the use of this material. For example,'very thin stainless steel foils, or steel and copper foils now available tinned to inhibit corrosion, may be used with appropriate adjustments.

The bonding or laminating of the sensor strips to the substrate is accomplished by mounting and spacing rolls of the sensor strip material on a common shaft and arranged so that they are let off from this unwind posi-' tion in a differential manner. One skilled in the art of laminating is well familiar with this tension compensating technique, so that further details are not necessary.

Referring now to the integrity of the sensor strips, previously mentioned (Page 8), if, for example, the

substrate in use stretches considerably in the direction transverse to the sensor strips, the length of the substrate diminishes as in stretching a rubber sheet in one direction. This causes the sensor strips to develop fairly large kinks at many points because the metal strips are inelastic and cannot follow the dimentional changes of the stretchy type of substrate. These kinks ultimately lead to fracturing. If a few (non-terminal) sensor strips fracture the pad can still function. When many do, the pad becomes deficient or useless. Minute kink development, over long use, with the non-stretchy substrates, is acceptable, because they do not propagate and ultimately lead to sensor strip fracture.

If the sensor strips are inordinately stretched in the same direction in which they are bonded, their elastic limit is generally exceeded and they fracture. In addition to this, constant and sharp flexing of the sensor strips by the movements of the sleeping user, tend to subject the sensor strips to flex-fatigue and they are subject to fracture when used with stretchy substrates. They do not fracture when the non-stretchable types specified are used in the pad structure. The use of nonstretchable, fairly flexible substrates, which do not bend sharply in use, solve the sensor strip fracture problem in a practical manner.

In the preferred embodiment of my invention the polarity collector strips, 13, FIG. 1, are of 2 mil plain aluminum foil which is electrically conductive on both its surfaces. The use of aluminum polarity collector strips in contact with the aluminum of the polarity tabs, 14, FIG. 4, eliminates galvanic corrosion.

I claim:

l. A urine flow sensor pad comprising: a laminate of a relatively thin and flexible, waterproof, electrically insulative crease resistant and essentially nonstretchable substrate;

a plurality of thin current conductive sensor strips respectively applied from continuous rolls thereof and bonded to one surface of said substrate in spaced and parallel arrangement;

said strips forming contacts on said pad operable due to electrolyte in urine thereon;

two polarity collector strip elements extending across opposite ends of said strips and electrically connected in overlapping contact therewith to different alternate and non-adjacent sensor strips;

a layer of insulation interposed between and coextensive with the overlapping ends of the remaining alternate and non-adjacent sensor strips and the corresponding portion of the adjacent collector strip; and

means for electrically connecting the two polarity collector strips to an external electrical circuit.

2. A urine flow sensor pad according to claim 1, in which (the sensor strips extend to opposite sides of the pad) the ends of alternate sensor strips are shaped to contact both sides of the connecting collector strip.

3. A urine flow sensor pad according to claim 1, in which all of said sensor strips are bonded to (one surface of) said substrate (and at least one of the polarity collector elements is positioned on the other surface) and are connected to said polarity collector strips via punched polarity tabs. 

1. A urine flow sensor pad comprising: a laminate of a relatively thin and flexible, waterproof, electrically insulative crease resistant and essentially non-stretchable substrate; a plurality of thin current conductive sensor strips respectively applied from continuous rolls thereof and bonded to one surface of said substrate in spaced and parallel arrangement; said strips forming contacts on said pad operable due to electrolyte in urine thereon; two polarity collector strip elements extending across opposite ends of said strips and electrically connected in overlapping contact therewith to different alternate and non-adjacent sensor strips; a layer of insulation interposed between and coextensive with the overlapping ends of the remaining alternate and nonadjacent sensor strips and the corresponding portion of the adjacent collector strip; and means for electrically connecting the two polarity collector strips to an external electrical circuit.
 2. A urine flow sensor pad according to claim 1, in which the ends of alternate sensor strips are shaped to contact both sides of the connecting collector strip.
 3. A urine flow sensor pad according to claim 1, in which all of said sensor strips are bonded to said substrate and are connected to said polarity collector strips via punched polarity tabs. 